Spark-plug.



W. S. THOMAS.

SPARK-PLUG.

APPLICATION man :uuzzs, 1911.

Patented Feb. 5,1918.

Mllzlwm 5. Th/(rm/ws.

WII4LIAM S. THOMAS, 015 LOCK HAVEN, PENNSYLVANIA.

SPARK-PLUG.

Specification of Letters Eatent.

Patented Feb. 5, 1918.

Application filed June 29, 1917. Serial No. 177,665.

. State of Pennsylvania, have invented certain new and useful Improvements in Spark- Plugs, of which the following is a specification.

My invention consists of an improved spark plug and is especially adapted for use in connection with internal combustion engines.

One object of my invention is to provide a spark plug in which the insulated electrode can be easily and quickly removed for cleaning purposes and can be put back into operative position without requiring any adjustment between the electrode points.

Another object is to so construct my invention that the insulated electrode can be removed or replaced by the use of but a single wrench and which has no means which exerts a mechanical pressure on the insulation of the insulated electrode.

A further object is to so make my improved spark plug that there will be no gaskets or washers to directly receive the impact of the explosion of gases but on the contrary will provide a durable metallic portion which will be capable of directly resisting the explosion of the gases.

These objects, and other advantageous ends which will be described hereinafter, I attain in the following manner, reference bein had to theaccompanying drawings in whic Figure 1 is an outside elevation of my improved spark plug.

Fig. 2 is a view of similar nature to Fig. 1 showing in section the securing means for the insulated electrode.

Fig. 3 is an elevation of the insulated electrode and a metallic jacket secured thereto, the jacket being shown in section.

Fig. 4 is a sectional elevation of the jacket as it appears prior to being forced upon the insulated electrode.

Referring to the drawings, 1 represents a metallic casing which provides an electrode and has a depending hollow stem 2 which is externally screw-threaded as shown at 3 so that the casing can be screwed within an en ine cylinder or the like.

he upper and ing 1 is made angular as shown at 4 in Fig. 1 so that the casing can be turned with a wrench when it is desired to either insert or outer surface of the casremove the same. 5 which is of larger diameter than the passage 6 in the stem 2. The bore 5 terminates at its bottom in a narrow shoulder 7 and a tapered or frusto-conical passage 8 extends downwardly from the shoulder 7 to the passage 6, thus the bore 5, frusto-conical passage 8, and passage 6 are all in communication with each other.

The casing 1 at its top is providedwith a cavity 9 WhlCll communicates with the bore 5 and is of lar er diameter, thus'providin a ledge 10. T eextreme upper portion 0 the cavity 9 is internally screw-threaded at 11 to receivean externally screw-threaded sleeve 12 of a nut 13, the opening 14 of the sleeve also extending through the nut 13. An elongated insulated electrode 15 has a. covering made of porcelain or similar material which is a non-conductor of electricity. This covering has an annular enlargement 16 within its length. enlargement 16, I place a metallic jacket 17.

This jacket is normally and preferably of the shape shown in-Fig. 4, the internal diameter as shown at 18 being substantially the same as the external diameter of the annular enlargement 16 of the insulated elec trode 15.

The lower portion of the jacket 17 is provided with an inturned flange 19 having a hole 20 through which the lower end 21 of the insulated electrode can extend. I preferably insert a washer or gasket 22 between the inner surface 23 of the flange 19 and the lower surface 24 of the annular enlargement 16 of the insulated electrode 15. This ket 22 can be of any desired construction, but I preferably use a gasket which is U- shape in'cross section and has a filling 25 of asbestos,

In addition to this, I preferably employ a ring gasket 26 around the upper portion 27 of the insulated electrode 15, this gasket 26 being pushed down into engagement with the upper surface 28 of the enlargement 16.

The upper edge portion'of the jacket 17 is reduced in thickness as shown at 29. After the jacket has been placed around the insulated electrode with the gaskets 22 and 26 in their positions as above described, pressure is applied to bend the edge portion 29 inwardly and at the same time to move the jacket upwardly with respect to the enlargement 16 of the insulated electrode 15, thus tightly binding the jacket to theinsulated Around this annular The casing 1 has a bore 7 electrode. If desired, 1 can place a coating or cement or filling material such as litharge so as to fill any crevices not filled by the compression of the gaskets 22 and 26.

By this arrangement it will be noted that the enlargement 16 of the insulated electrode 15 will be tightly bound within the jacket 17, and the pressure of the jacket 17 is sufficient to tightly bind the gaskets in their respective positions.

The lower surface 30 of the jacket is designed to rest upon the shoulder 7 in the casing 1, the external diameter of the jacket being such as to snugly fit within the bore 5. Furthermore, by reducing the upper edge portion 29 of the jacket 17, a ledge 31 is provided, and the height of the jacket 17 is such that when the surface 30 is in engagement with the shoulder 7, the led e 31 will be in substantial alinement with t e ledge 10. A gasket 32 is placed around the insulated electrode 15 so as to extend across the part ing between the jacket 17 and the casin 1, and to rest upon the ledges 1.0 and 31. his gasket can be made of copper and asbestos or other suitable material, and the lower end of the threaded sleeve 12 is designed to abut and compress the same to form a seal for the parting between the jacket 17 and the bore 5.

It will be noted that the pressure of the nut 13 and sleeve 12 will be resisted by the jacket and not by the porcelain, thus it is practically impossible to fracture the porcelain no matter how tightly the sleeve 12 is screwed against the gasket 82.

The passage 6 in the casing 1 is made sufficiently large to provide ample space between the end 21 of the insulated electrode and the inner surface of the stem 2. Furthermore, the frusto-conical passage 8 forms a shed for any carbon particles and ermits the ready cleaning of the casing a er the insulated elect-rode with the jacket thereon has been removed.

The point of the insulated electrode is preferably positioned in axial alinement with the jacket 17 so that no matter'how much the'insulated electrode is turned, the point 33 will always occupy the same relative position to the point Stof the electrode formed by the casing 1. This is an extremely desirable feature'in a spark plug in which the insulated electrode can be removed from the casing or body portion, since it requires no' re-adjustment of the electrode points.

In this connect-ion it will be further noted that with my improved spark plug it is not necessary LO remove the casing 1 from the engine cylinder when it is desired to clean the plug. It ismerely necessary to remove the nut 13 after which the entire insulated. electrode with the jacket 17 thereon can be quickly and easily lifted out of the casing 1 With my improved spark plug it is quite possible to clean all the parts in the dark because a readjustment of the electrodes is not necessary and only one wrench is, required, namely the wrench to turn the nut 13.

It will be further noted that the mere seating of the jacket 17 within the bore 5 and. on the shoulder 7 serves to properly position the electrode points. In use, the gases during th explosions impact with the bottom of the metallic jacket 17, and since this jacket is backed by the nut 18 and sleeve 12, it is fully capable of resisting all pressure due to the explosion of the gas without materially compressing the insulation of the electrode 15.

In addition to the above mentioned advantageous features of my improved spark plug, it is a source of economy to the user since it the insulated electrode is injured, it is merely necessary to insert another insulated electrode having the jacket 17 thereon, and it is not necessary for him to discard or remove the casing 1.

While I have described my invention as taking a parlicular form, it will be understood that the various parts of my invenlion may be changed without departing from the spirit thereof, and hence I do not limit myself to the precise construction set forth, but consider that I am at libert Y to make such changes and alterations as fairly come within the scope of the appended claims,

Having thus described my invention, what I claim as new and desire to secure by Lettcrs Patent is:

1. A spark plug including a casing having a bore terminating in shoulder, an' insulated electrode, a jacket on said elec trode fitting the bore and engaging said shoulder, said casing and said jacket providing ledges at positions remote from said shoulder, a gasket resting jointly on-said lodges, and means for forcibly pressing the gasket into engagement with said ledges, substantially as described.

2. A spark plug including a casing hav ing a bore terminating in a shoulder, an insulated electrode, a jacket on said electrode fitting the bore and engaging said shoulder, said casing and said j: cket providing ledges at positions remote from said shoulder, a gasket resting jointly on said ledges, means for forcibly pressing the gasket into en gagement with said ledges, said ledges being 26 shoulder, and

lated electrode, a jacket on said electrode 'fitting the bore and, engaging said shoulder, said casing and said jacket providing ledges at ositions remote from said shoulder, a gas et resting jointly on said ledges, said 0 casing having a cavity intersecting its ledge,

said cavity being internall screw-threaded, a nut havlng an opening t rough which the insulated electrode freely extends, a threaded sleeve projecting'from said nut and designed to engage the threads of said cavity,

said sleeve being designed to force said gas ket in engagement with both of said ledges,

substantially as described.

4. A spark plug including a casing having'a bore terminating in a shoulder, an

1 insulated electrode, a jacket on said electrode fitting the bore and engaging the shoulder, said casing and said acket pro viding ledges at POSIiZ iODS remote from said securing means adapted tov be forced into engagement with both of said ledges and to form a seal for the parting therebetween, substantial] as described.

' 5. A spark plug including a casinghaving a bore terminating in a shoulder, an insu ated electrode having an enlargement, a jacket surrounding said enlargement and compressed into securing engagement therewith, said jacket having an inturned flange designed to rest on said shoulder, said jacket having a ledge oppositely disposed to said flange, said casing having a ledge in substantial alinement with the ledge of said jacket, a 'gasket for, joint engagement with said ledges, and means for pressing the gasket into engagement with said ledges, substantially as described.

6. A spark plug including a casing hav- 7 ing a bore terminating in a shoulder, an .insulated GIQCt/I'OdGhEVIIIg an enlargement, a jacket surrounding said enlargement and compressed into securing engagement therewith, said jacket having an inturned flange designed to rest on said shoulder, said jacket having a ledge oppositely disposed to said flange, said casing having a ledge in substantial ,alinement with the ledge of said jacket, a gasket for joint engagement with said ledges, said casing having a screwthreaded cavity intersecting its ledge, a nut having a threaded sleeve for engagement with said screw-threads of the cavity and designed to force said gasket into engagement with both of said ledges, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

WILLIAM S. THOMAS. 

